CAREER: Integrated Stratigraphic and Hydrogeologic Aquifer Analysis: Toward Improved Multi-scale Characterization of Alluvial Aquifer Systems

[133666 . weissmann]地下水系统中污染物运移和命运的精确建模和预测要求我们产生详细的含水层特征。最近，PI及其同事开发了一种新的层序地层学方法来表征水相分布，用于河流主导的冲积扇系统的地下水模型，从而整合地质和水文评估。从这项工作中得出的几个问题指导了本计划的研究项目，包括：1)在其他冲积扇系统中是否存在序列和系统域；2)以富含粘土的成熟古土壤为界的层序，将地下水划分为水文地层单元；3)层序地层学能否为其他冲积扇系统的地下水模拟提供改进框架。通过劳伦斯利弗莫尔国家实验室（LLNL）的沉积学、古地质学和水文地质学分析，我们打算测试由这些问题形成的假设。LLNL拥有大量的岩心、地球物理测井和三维水文测试数据。LLNL遗址的初步工作表明，成熟的古土壤可能束缚水文地层单元，从而表明存在古土壤束缚层序，层序几何形状可能强烈影响含水层的水动力学。通过这项工作，我们将(1)描述之前收集的约6000米的岩心，(2)评估古土壤形态和化学，(3)模拟地层、多尺度相分布、地下水流动和复杂含水层系统中的污染物输送，以及(4)评估数据价值，以评估类似地质环境下未来工作的最低数据要求。这些模型将根据含水层测试和污染物浓度数据进行测试。这项工作的一个主要目标是让许多学生研究人员参与这个项目，因此一些学生将直接参与日常的研究活动。此外，本研究的各个方面将被纳入课堂活动，在含水层和油藏评估课程中，学生将分析岩心，在一个小地点构建三维地层格架，并在现场模拟非均质性。这不仅将使学生接触到研究项目，而且将为建模结果的不确定性评估提供地层特征的多种“实现”。

0133666WeissmannAccurate modeling and prediction of contaminant transport and fate in groundwater systems requires that we produce detailed aquifer characterizations. Recently, the PI and colleagues developed a novel sequence stratigraphic approach to characterizing hydrofacies distributions for use in groundwater models on a stream-dominated alluvial fan system, thus integrating geological and hydrological assessment. Several questions resulted from this work that guides this proposed research project, including: 1) do sequences and systems tracts exist in other alluvial fan systems; 2) do sequences, bounded by clay-rich mature paleosols, compartmentalize groundwater flow into hydrostratigraphic units; and 3) can sequence stratigraphy provide a framework for improved groundwater modeling on other alluvial fan systems. Through sedimentologic, paleopedologic, and hydrogeologic analysis at the Lawrence Livermore National Laboratory (LLNL), a site with extensive core, geophysical well log, and 3D hydrologic test data, we intend to test hypotheses formed from these questions. Preliminary work at the LLNL site indicates that mature paleosols may bound hydrostratigraphic units, thus indicating that paleosol bounded sequences exist and that sequence geometry may strongly influence aquifer hydrodynamics. Through this work, we will (1) describe about 6000 meters of previously collected core, (2) assess paleosol morphology and chemistry, (3) model the stratigraphy, multi-scale facies distributions, groundwater flow, and contaminant transport within this complex aquifer system, and (4) assess data value to evaluate minimum data requirements for future work in similar geologic settings. These models will be tested against aquifer test and contaminant concentration data. A major objective of this work is to involve many student researchers in this project, thus several students will be directly involved in daily research activities. Additionally, aspects of this research will be incorporated into classroom activities, where students in an aquifer and petroleum reservoir assessment course will analyze core, construct the 3-D stratigraphic framework at a small site, and model the heterogeneity at the site. This will not only expose students to the research project, but will provide multiple 'realizations' of the stratigraphic character for uncertainty assessment of the modeling results.